Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings In vertebrates – The CNS is composed of the brain and spinal cord – The peripheral nervous system (PNS) is composed of nerves and ganglia

Fig Peripheral nervous system (PNS) Cranial nerves Brain Central nervous system (CNS) Ganglia outside CNS Spinal nerves Spinal cord

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Organization of the Vertebrate Nervous System The spinal cord conveys information from the brain to the PNS The spinal cord also produces reflexes independently of the brain A reflex is the body’s automatic response to a stimulus – For example, a doctor uses a mallet to trigger a knee-jerk reflex

Fig White matter Cell body of sensory neuron in dorsal root ganglion Spinal cord (cross section) Gray matter Hamstring muscle Quadriceps muscle Sensory neuron Motor neuron Interneuron

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Peripheral Nervous System The PNS transmits information to and from the CNS and regulates movement and the internal environment In the PNS, afferent neurons transmit information to the CNS and efferent neurons transmit information away from the CNS Cranial nerves originate in the brain and mostly terminate in organs of the head and upper body Spinal nerves originate in the spinal cord and extend to parts of the body below the head

Fig Efferent neurons Locomotion Motor system Autonomic nervous system Afferent (sensory) neurons PNS Hearing

Fig Efferent neurons Locomotion Motor system Autonomic nervous system Afferent (sensory) neurons PNS Hearing CirculationGas exchangeDigestion Hormone action Enteric division Sympathetic division Parasympathetic division

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The PNS has two functional components: the motor system and the autonomic nervous system The motor system carries signals to skeletal muscles and is voluntary The autonomic nervous system regulates the internal environment in an involuntary manner

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The autonomic nervous system has sympathetic, parasympathetic, and enteric divisions The sympathetic and parasympathetic divisions have antagonistic effects on target organs

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The sympathetic division correlates with the “fight-or-flight” response The parasympathetic division promotes a return to “rest and digest” The enteric division controls activity of the digestive tract, pancreas, and gallbladder

Fig Stimulates glucose release from liver; inhibits gallbladder Dilates pupil of eye Parasympathetic division Sympathetic division Action on target organs: Inhibits salivary gland secretion Accelerates heart Relaxes bronchi in lungs Inhibits activity of stomach and intestines Inhibits activity of pancreas Stimulates adrenal medulla Inhibits emptying of bladder Promotes ejaculation and vaginal contractions Constricts pupil of eye Stimulates salivary gland secretion Constricts bronchi in lungs Slows heart Stimulates activity of stomach and intestines Stimulates activity of pancreas Stimulates gallbladder Promotes emptying of bladder Promotes erection of genitals Action on target organs: Cervical Sympathetic ganglia Thoracic Lumbar Synapse Sacral

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 49.3: The cerebral cortex controls voluntary movement and cognitive functions Each side of the cerebral cortex has four lobes: frontal, temporal, occipital, and parietal Each lobe contains primary sensory areas and association areas where information is integrated

Fig Speech Occipital lobe Vision Temporal lobe Frontal lobe Parietal lobe Somatosensory association area Frontal association area Visual association area Reading Taste Hearing Auditory association area Speech Smell Motor cortex Somatosensory cortex

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Information Processing in the Cerebral Cortex The cerebral cortex receives input from sensory organs and somatosensory receptors Specific types of sensory input enter the primary sensory areas of the brain lobes Adjacent areas process features in the sensory input and integrate information from different sensory areas In the somatosensory and motor cortices, neurons are distributed according to the body part that generates sensory input or receives motor input

Fig Primary somatosensory cortex Frontal lobe Pharynx Parietal lobe Teeth Gums Jaw Tongue Lips Face Nose Eye Thumb Fingers Hand Forearm Elbow Upper arm Head Neck Trunk Hip Leg Genitals Abdominal organs Primary motor cortex Tongue Toes Jaw Lips Face Eye Brow Neck Fingers Hand Wrist Forearm Elbow Shoulder Trunk Hip Knee Thumb